261205121001 has 16 divisors (see below), whose sum is σ = 379966095360. Its totient is φ = 158293061520.

The previous prime is 261205120999. The next prime is 261205121011. The reversal of 261205121001 is 100121502162.

It is not a de Polignac number, because 261205121001 - 2¹ = 261205120999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261205121011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 86680 + ... + 727958.

It is an arithmetic number, because the mean of its divisors is an integer number (23747880960).

Almost surely, 2^261205121001 is an apocalyptic number.

It is an amenable number.

261205121001 is a deficient number, since it is larger than the sum of its proper divisors (118760974359).

261205121001 is a wasteful number, since it uses less digits than its factorization.

261205121001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 653636.

The product of its (nonzero) digits is 240, while the sum is 21.

Adding to 261205121001 its reverse (100121502162), we get a palindrome (361326623163).

The spelling of 261205121001 in words is "two hundred sixty-one billion, two hundred five million, one hundred twenty-one thousand, one".